For many years, large commercial bakeries have manually prepared batches of ingredients for mixing into large "doughs". These batches which are pre-mixed typically include liquid batches of several ingredients. These ingredients include soy oil, di-malt, yeast, fructose, honey, refiner's syrup, vinegar, and lecithin. These ingredients, along with the dry ingredients of mainly flour, are mixed in large mixers before being further processed into smaller loaves for the baking of bread and other similar bakery products. As an example, for bread, a first set of liquids comprising soy oil, dimalt, water and yeast are added to a "sponge dough" as the materials are first mixed. This sponge dough is then permitted to rise in a dough room before being further processed in a second mixer with a second batch of liquid ingredients comprising liquid sugar (fructose), honey, refiner's syrup (molasses), vinegar, di-malt, lecithin, yeast, and water. In the prior art, these liquid ingredients comprising these two batches (except for water) were hand measured into a bucket which would then be manually dumped into the mixer at each of the two above-described stages of the baking process.
This hand preparation and mixing of liquid ingredients at these two stages of the baking process was very inexact. The amount of each ingredient actually added to the bucket depended entirely upon the measurement made by the operator. Additionally, even if the operator were to make very exacting measurements, a not insubstantial amount of residue remained in the bucket after it was dumped into the mixer. Furthermore, the composition of this residue was inexact and varied from mix to mix such that it could not be adequately accounted for. It should also be noted that the water component of these liquid additions was not actually measured and added by bucket due to the fact that substantially more water is added at each of these two liquid additions. For example, in a typical baking process for bread or the like, 50-60 lbs. of liquid ingredients other than water could be required while the water component might be as much as 400 lbs. As was consistent with the attention given the "active" ingredients, the amount and temperature of the water actually added was never adequately monitored and controlled. Considerable inaccuracy existed in the addition of liquid ingredients, including water, which produced a variation in the product produced by the baking process. This problem became even more acute as the inventors herein participated in an effort to automate the baking process.
In automating this process, a liquid weigh scale hopper and water flush arrangement was developed which permited a batch of liquid ingredients to be prepared and then flushed completely into a mixer while leaving virtually no residue in the hopper or delivery tube. This was achieved by spraying the chilled water liquid ingredient into the hopper such that it fills it without overflowing to gravitationally help push the liquid batch out of the hopper and flush it while doing so. The liquid hopper is typically sized to hold approximately 180 lbs. of liquid ingredients. As mentioned above, the liquid ingredients comprising a typical batch would range from 50-60 This permits the liquid scale to be loaded to its maximum with an additional 120-130 lbs. of water whose weight helps force the liquid ingredients out through a valve located at the bottom of the hopper. Additionally, the water dilutes the top portion of the liquid ingredient batch which helps eliminate any residue which might form into a ring around the inside of the liquid scale at its fill line, as well as facilitating the flushing of the last portion of the liquid batch out of the hopper and through the delivery tube. Even after the scale is maximally loaded with water, in a typical mix of 400 lbs. of water, another 250 lbs. or more of water is then sprayed against the inside of the hopper and ensures a substantially clean flush of the inside thereof. This development is the subject of a separate patent filing.
In implementing the liquid weigh scale hopper, problems were noticed with regard to the prior art water supply system. Water was delivered in inaccurate quantities and at seemingly uncontrolled temperature from batch-to-batch. Therefore, in order to properly implement and automate the pre-mix batching of the liquids, the inventors herein developed a water control system for accurately monitoring and controlling the water temperature and quantity so as to satisfy the water requirements for each pre-mix batch of liquid ingredients. In essence, this water control includes a temperature sensor and flow meter mounted in the single supply pipe which carries the water to the weigh hopper, a valve set for controlling the flow of water from each of the three water sources, and a computer for monitoring and controlling these various components. The temperature sensor and flow meter are mounted within the first several feet of pipe following the juncture at which water from each of the water sources is plumbed together. Thus, the computer can accurately monitor and control water conditions at their source. Additionally, the valve set includes three on/off valves, one for each of the cold water, hot water, and tap water sources, as well as two modulating valves to vary the flow of water from the hot water and tap water sources. A modulating valve is not provided in the cold water line as cold water is produced at a temperature below that required by the baking process and then tempered up to the desired temperature by water from each of the other two sources as will be explained in greater detail below.
While controlling the flow of water from three water sources in order to provide a single substantial stream of water at a pre-determined temperature might ordinarily seem to be relatively routine, such is not actually the case. First of all, water must be provided in a substantial stream in order to satisfy the spraying requirements of the related invention described above. Furthermore, water should be provided rapidly in order to not interrupt the baking process which is in progress when the liquids are dumped into the mixer from the liquid scale hopper. Because of these high flow rates, the temperature sensor will produce an output which does not exactly track the actual temperature of the water because its response time is not fast enough to follow that temperature change. Therefore, the temperature sensor's response must be adjusted so as to more accurately predict the actual water temperature. Additionally, the control process must be delayed for a pre-determined time delay at the start of each production so that the stale water temperature is not presented to the control as the fresh water temperature. As can be appreciated, as the water sits in the pipes between production runs, its temperature drifts and is not representative of the water temperature which results from the valve settings. Therefore, a time delay is required in order to avoid an incorrect adjustment in valve setting. Still other problems were encountered in trying to control water from three sources. In order to utilize three sources, the inventors have implemented a phase-in control algorithm. With this algorithm, cold water is provided at full flow, tap water is then added by a modulating valve until it reaches 80% of full flow, or until the desired water temperature is reached. At that point, if the output water temperature is still below desired, hot water is throttled in by its modulating valve. In implementing the water control of the present invention, it is believed that tap water need only be used in the summertime in order to raise the cold water temperature to a desired water temperature of a nominal 40.degree. F. However, in wintertime it is believed that the uncontrolled tap water temperature is not sufficiently high enough to achieve the correct temperature by itself. Thus, in winter hot water would also be throttled in such that water from all three sources would be required to achieve the substantial stream of water for flushing the liquid scale hopper of the related invention.
By way of example, the 400 lbs. of water mentioned above for a typical batch is typically provided in 11/4minutes. This is approximately 37 gallons per minute of water. As the single supply pipe is typically a 21/4inch nominal O.D. copper pipe (insulated), one can readily see that a substantial flow rate is experienced in order to achieve these water delivery parameters. This flow rate is so substantial that it exceeds the response time of the temperature sensor, as mentioned above. Additionally, it creates a problem for the flow meter as well in that the magnetic coupling relied on to couple the metering disk with the flow disk will be overcome in some situations. For example, should the cold water be turned on first at full flow, the significant in-rush would tend to decouple the flow meter such that it would not accurately track the flow rate of water flowing through the single supply pipe. Therefore, the computer has a control algorithm which requires the tap water line to be throttled open to 20% flow prior to the cold water being turned on. This helps prevent any sudden in-rush from a full off position which could decouple the flow meter and result in faulty flow readings. A flow meter which utilizes a magnetic coupling not only provides less maintenance in that there is no water seal, but it is also less expensive. Hence, use of a magnetically coupled flow meter is highly desirable. For the same reason, valves are utilized with pulse width modulated control interfaces instead of more expensive valves with 4-20 milliamp control interfaces. These modulating valves are pulsed open and closed by the computer but there is no automatic position indication provided to the computer as with the 4-20 milliamp control interface valves. Instead, the computer essentially re-initializes each modulating valve at the start of each water production by pulsing it to close, keeping track of the number of pulses required to achieve close, and then returning it to its previous setting. In this operating mode, the modulating valves remain in their set position from the end of one production to the start of another, and this set position is accurately measured by using the control routine which re-initializes the valve.
While the principal advantages and features of the present invention have been mentioned above, a greater understanding may be attained by referring to the drawing and description of the preferred embodiment which follow.